Telephone transmitter and receiver



Pl'il 17, 1934 F. scHrFFL TELEPHONE TRANSMITTER AND RECEIVER Filed March 28, 1931 2 Sheets-Sheet l annual,

INVENTOR FRANK 5CH\FFL BY gM-p-U/ ATTORNEY April 17, 1934. F SCHH-'FL 1,955,390

TELEPHONE TRANSMITTER AND RECEIVER Filed March 28. 1931 2 Sheets-Sheet 2 ooooooaoooossooooocooo ooQooooooooooooaaoooso INVENTOR FRANK SCHFFL *BY ATTORNEY Patented Apr. 17, 1934 UNlTED STATES PTE GFFIC Frank Schiifi, Paris, France, assigner to Radio Corporation of America, a corporation of Dela- War@ Application March 28, 1931, Serial No. 525,904 En Great Britain April 3, 1930 12 Claims.

The present invention relates to a telephone transmitter or receiver, and more particularly to such an instrument for use in wireless telephony or in connection with the production and exhibition of sound records as for talking motion pictures.

The object of my invention is to provide an improved instrument for converting the energy of variable electric currents into sound wave energy, and conversely for converting sound waves into variable electrical currents.

More particularly, the object of my invention is to provide an instrument, for example, a telephone receiver, cr as it is more commonly termed,

a loudspeaker, which will reproduce, as sound, electrical oscillations over the whole rangeV of audio frequencies without distortion and with a maximum efficiency.

These and various other objects of my invention will become apparent from the. following specication taken in connection with the appended drawings.

In accomplishing the objects of my invention, I provide in a telephone transmitter or receiver a preferably non-magnetic metallic diaphragm disposed between a pair of pancake coils adapted to carry a constant direct current. A second pair of coils wound similarly and arranged concentrically' with the rst coils is provided either 3u for the purpose of receiving, by induction, the alternating or varying current corresponding to the mechanical vibrations of the diaphragm, in the` case of a transmitter, or for .carrying such currents to produce corresponding mechanical vibrations of said diaphragm, in the case of a receiver.

Having thus briefly described my invention, attention is invited to the-accompanying drawings in which like parts are designated by the same reference numerals, and in which;

Fig. 1 is a front elevation of one embodiment of my invention;

Fig. 2 is a vertical diametrical section of the transmitter or receiver shown .in Fig. 1;

Figs. 3A, B, C and D are cross sections of part of the coils illustrating the various connections and arrangements thereof; and,

Figs. 4A, B, C and D are wiring diagrams corresponding to the coil arrangements shown in Figs. 3A,B, C and D respectively.

Referring now more particularly to Figs. 1 and 2 which illustrate an energy converting device comprising one embodiment of my invention, 1 represents a spider made preferably of wood and 55 shaped as shown. A second spider 2 is also provided, and between the two spiders are provided spacing rings 3, the inner surfaces of which are covered at 4 and 5 respectively, with some soft material such as hair-felt, said felted surfaces serving to clamp the diaphragm 6 between the spacer 4 and 5. For clamping the spiders and spacers together and thus holding the diaphragm 6, there are provided bolts 7 and wing-nuts 8.

Also carried by the spiders l and 2 are pancake coils each composed of a plurality of annular coils maintained in spacial relationship in order to provide interstices to permit ingress or egress of sound waves to and from the diaphragm. Each of these annular coils is composed of a voice coil winding 9 and a eld coil winding 10. The eld coil windings are connected in series so that the field produced by each winding 10 on one side of the diaphragm combines with the eld produced by each other winding, and the combined eld winding is connected with a direct current supply source. The set of field coil windings on the opposite side of the diaphragm are similarly connected but so disposed that the field set up by them on this side of the diaphragm opposes the eld set up by the coils on the opposite side.

The voice current coil windings 9 may be similarly wound. They may be disposed, as shown in Figs. 1, 2 and 3A, upon the faces of the eld coil windings, adjacent to the diaphragm. Each winding will be composed of a lesser number of turns than the field coil windings. The connections of the voice and field coils 0I" this form of my invention is shown more particularly in Fig. 4A, which shows that the field coil windings are connected to a direct current source, the field produced by each set of field coil windings being combined. The voice coil windings are fed by current representative of the voice frequencies produced by source 11 and transmitted through transformer 12.

The diaphragm 6 is preferably made of nonmagnetic metal such as aluminum, in order to reduce hysteresis and eddy current losses to a minimum. It may be clamped, as shown and described above, between the field structure supports or may be suspended freely therebetween. When my telephone instrument is acting as a receiving instrument, the direct current passing through the field coil windings sets up a field, radial with respect to the diaphragm 6. The current passing through the voice coil windings induces similar circular currents in the diaphragm, which currents cause a motion of the diaphragm through a field produced by the direct current Winding. 110

. ed adjacent thereto.

.i members.

It is to be noted that the eld produced by the ield coil windings extends with practically equal intensity the entire extent of the diaphragm, and also that the currents induced in the diaphragm by the voice coil windings will be of practically equal intensity throughout the entire diaphragm. Therefore, the motion of the diaphragm will be practically uniform depending upon the rigidity of its mounting. As above described, the felt mounting of the diaphragm permits motion of the diaphragm bodily throughout its entire extent. If freely mounted in accordance with the above mentioned variation, such mounting of the diaphragm will permit even greater motion throughout its entire extent.

When my telephone instrument is operating as a transmitting device, the field produced by the eld coil windings is the same as that just described, extending radially with respect to the diaphragm. Motion of the said diaphragm relative to said field as caused by impinging sound waves, generates circular currents in said diaphragm, and the currents thus generated, induce similar currents in the voice coil windings mount- The output of the voice coil windings, therefore, is a current representative of the sound waves falling upon the diaphragm.

Referring now to Figs. 3B and 4B, an alternative arrangement is shown in which the inductors composing the voice coil sections are wound with the inductors composing the eld coil sections. The current is supplied to these coils in the same manner as it is supplied to the coils connected in accordance with the showing of Figs. 3A and 4A described above.

Referring now to Figs. 3C and 4C, another alternative arrangement of the field and voice coils is shown. The iield coil windings l0 are disposed in this instance upon the spider as in the previously described arrangement, but the voice coil windings are arranged on the diaphragm so as to move with or be moved thereby. The connection of these windings is the same as the connection of the voice coils in Figs. 3A and 3B however.

The fourth arrangement is shown in Figs. 3D and 4D. 1n this arrangement a double diaphragm is utilized and the voice current coil windings are arranged between the two diaphragm The connections of these windings, however, are the same as the connections of the windings of the previously described embodiments, and are as is shown clearly in Figs. 3D and 4D.

Having thus described my invention and its operation, attention is invited to the fact that various modiiications may be made therein falling, however, within its scope, and that I am therefore not to be limited to the specic embodiment shown and described, but to the actual scope of my invention as set forth in the appended claims.

I claim:

l. A telephone instrument comprising a nonmagnetic metallic diaphragm, a rield coil adjacent thereto and adapted to produce a radial field about said diaphragm, and a second coil inductively related to said diaphragm whereby similar currents will obtain in said coil and said diaphragm.

2. A telephone instrument comprising a iixed pancake coil comprising two windings and a diaphragm consisting of a sheet of non-magnetic conducting material adjacent and parallel thereto, covering substantially the entire area of said coil.

3. A telephone instrument consisting of a pair of like pancake coils mounted on the opposite sides of an electrically conducting diaphragm, each of said coils being composed of two windings, one of which is adapted to carry a variable current, and the other of which is adapted to carry a direct current, the electrical connections of said windings being such that the eifect of direct current is to produce a constant radial magnetic field in the diaphragm, while the Variable currents produce a variable magnetic iield perpendicular to the diaphragm.

4. A telephone instrument consisting of a diaphragm of electrical conducting non-magnetic material, and a pancake coil mounted adjacent to and parallel with said diaphragm and distributing over an area substantially equal to that of the diaphragm, said coil being composed of two windings, one of which is adapted to carry a direct current whereby impingement of sound waves on said diaphragm resulting in vibration thereof will generate variable currents in the second winding of said coils.

5. In a telephone instrument, a supporting structure, a diaphragm of non-magnetic conducting material mounted therein, pancake coils mounted at opposite sides thereof in close parallel relation thereto, each of said coils consisting of a series of annular concentric sections, spaced apart from one another, and each of said sections comprising two windings.

6. A telephone instrument comprising a fixed pancake coil, a diaphragm consisting of a sheet of non-magnetic conducting material adjacent and parallel thereto, and covering substantially the entire area of the coil, and a second pancake coil affixed to said diaphragm.

7. A telephone instrument comprising a iixed pancake coil, a diaphragm of non-magnetic material adjacent and parallel thereto covering substantially the entire area of the coil, said coil being adapted to carry a direct current which produces a radial magnetic eld in said diaphragm, whereby the vibration of said diaphragm in response to sound Waves impinging thereon will cause the generation in the diaphragm of variable currents corresponding to the sound waves, and a second pancake coil axed to said diaphragm whereby the variable currents generated in said diaphragm will induce corresponding currents in said coil.

8. A telephone instrument comprising aixed windings, a diaphragm of conducting material adjacent thereto, said windings being adapted to carry a direct current whereby a radial magnetic iield may be produced throughout substantially the entire area of the diaphragm, and a second winding aiiixed to said diaphragm and adapted to carry a variable current which will induce a corresponding variable current in said diaphragm and produce vibration thereof by reason of the reaction between the variable currents induced therein and the variable magnetic iield about the diaphragm produced by the direct current.

9. A telephone instrument consisting of a diaphragm of electrical conducting non-magnetic material, a coil aixed to said diaphragm and a pancake coil mounted adjacent to and parallel with said diaphragm and distributing over an area substantially equal to that of the diaphragm, said coil being adapted to carry a direct current, whereby impingement of the sound Waves on said diaphragm resulting in vibration thereof Will generate variable currents in the coil attached to said diaphragm.

10. A telephone instrument consisting of a supporting structure, a vibratory diaphragm of conducting material mounted Within said support, a pair of pancake coils mounted upon the opposite sides in close parallel relation to the diaphragm, and a pair of coils mounted upon the opposite sides of said diaphragm, said xed coils being adapted to carry a direct current, and said movable coils being adapted to carry a Voice current, and each of said coils being formed in annular concentric sections spaced apart from one another.

11. In a telephone instrument, a supporting structure, a diaphragm of non-magnetic conducting material mounted therein, pancake coils at the opposite sides thereof in close parallel relation thereto, each of said coils consisting of a series of annular concentric sections spaced apart from one another, and movable pancake coils mounted on the opposite sides of said diaphragm, and each consisting of a series of annular concentric sections spaced apart from one another.

12. A device of the type described including an electrically conducting diaphragm, a pair of direct current coils mounted on the opposite sides or said diaphragm to produce a constant radial magnetic eld therein, and a variable current coil mounted upon said diaphragm to produce a Variable magnetic eld perpendicular to said diaphragm.

FRANK SCHIFFL. 

